The present invention relates to a switching mechanism for a conveying system for the conveying of a product stream of products arranged in an overlapping formation by means of a pressing belt pair and also to a conveying system equipped with such a switching mechanism.
Conveying systems for the conveying of products arranged in an overlapping formation by means of two pressing belts are basically known and enable, amongst other things, an overhead conveyance of the products. In order to direct the overlapping formation from one conveying system to a second or to a third conveying system it has hitherto been the practice to build up two complete conveying systems with a floor belt switching mechanism being inserted before them. In this way, it is possible to effect transport selectively into the one or other conveying system. A disadvantage of this is, however, the fact that half of the conveying path must be realised twice and that for this floor space must be made available which is frequently restricted in printing works.
It is the object of the present invention to provide an apparatus by which conveyor paths and space requirements can be reduced in a conveying system of the initially named kind, with it simultaneously being possible to achieve a flexible deflection of the overlapping formation onto various conveying paths and with any desired arrangement of the switching mechanism in the space.
This object is satisfied through the features of claim 1 and in particular by a switching mechanism in which a stationary base frame and also a movable pivotal element are provided to set different distributor positions. In accordance with the invention, at least one rider belt is provided which replaces one of the two press belts in the region of the switching mechanism. One deflection roller for this rider belt is secured to the base frame and a further deflection roller of this rider belt is secured to the pivotal element. Thus, in accordance with the invention, the product stream can be guided into different directions by pivoting of the movable pivotal element, with the pressure on the overlapping formation being maintained, since the first rider belt changes its position together with the pivotal element. Since one deflection roller of the first rider belt is simultaneously of stationary position, the rider belt is always pressed against the press belt which is guided through the switching mechanism.
With the switching mechanism of the invention, product streams in overlapping formation can be conveyed and deflected in any desired arrangement and, in particular, also overhead, i.e. in this case a floor area does not need to be made available. Moreover, larger conveyor paths can be spared, since it is possible to direct the overlapping stream in a fully clamped state onto different conveyor paths.
Advantageous embodiments of the invention are described in the description, in the Figures.
In accordance with a first advantageous embodiment of the invention deflection rollers for further rider belts can be secured to the pivotal element, with the rider belts preferably overlapping and being arranged in different planes. Through the provision of further rider belts, which are pivoted together with the pivotal element, a continuous pressing of the overlapping formation is ensured in every position of the switching mechanism. In particular, the arrangement of adjacent overlapping rider belts enables a continuous pressing of the overlapping formation.
A tensioning roller which is secured to a compensation element, which moves under prestress on a pivotal movement of the pivotal element, is preferably provided for the first rider belt. A compensation element of this kind can, for example, be realised in the form of a clamping lever, which always prestresses the rider belt so that it is pressed against the product stream. On pivoting of the pivotal element, the one deflection roller of the rider belt moves relative to the other deflection roller which is secured in a stationary position, so that an extension or a shortening of the active region of the rider belt along the product stream arises. With this arrangement the tensioning roller ensures that the first rider belt is always so tensioned that the desired pressing pressure always remains set with a shortening or extension of the effective region of the rider belt.
That pressing belt which is not replaced by the first rider belt can be guided, in accordance with a further embodiment of the invention, about a deflection roller of stationary position, with the radius of the deflection roller corresponding substantially to the minimum track radius of the product stream in the region of the switching mechanism. This deflection roller of stationary position thus determines the minimum track radius.
The maximum track radius can be infinite with the switching mechanism of the invention. i.e., in accordance with the invention, it is possible to achieve a straight run of the products in one conveying position of the switching mechanism.
It is advantageous when the other press belt is guided, after passing partly around the deflection roller of stationary position, around a further deflection roller with a smaller radius which is secured to the pivotal element. In this way, the press belt can also be used after passing partly around the deflection roller of stationary position as a counterpressure belt for a further rider belt. The radius ratio between the deflection roller of stationary position and the further deflection roller with a smaller radius can amount to about 3:1.
In accordance with a further advantageous embodiment a rider belt is guided around the deflection roller of stationary position and around at least one further deflection roller which is secured to the pivotal element. In this way, the support of the product stream can be further improved, with the synchronisation being ensured by the incorporation of the deflection roller of stationary position.
The first rider belt and at least one further rider belt are preferably arranged on one side of the product stream and the stationary deflection roller and a further rider belt on the other side of the product stream. In this way the product stream is reliably guided in every position of the pivotal element, with a decoupling between the input side and the output side of the switching mechanism simultaneously taking place. If, in addition, the rider belts have a product thickness adaptation at one side, then product streams of different thickness can be conveyed through the switching mechanism without problem without a new setting having to be effected.
It is particularly advantageous when the pivotal element is pivotal about 90xc2x0. In this case it is possible to feed in a straight line from an incoming pressing belt pair to a departing pressing belt pair, or to bring about a 90xc2x0 deflection from the incoming pressing belt pair. At the same time all intermediate positions are naturally also possible in which the overlapping formation can be transferred to further departing pressing belt pairs. For the sake of completeness it should be noted that the terms arriving pressing belt pair and departing pressing belt pair have only been selected for the sake of better description, naturally it is also possible to operate the switching mechanism of the invention in every conveying direction.
It is particularly advantageous designwise when the pivot axis of the pivotal element and the axis of rotation of the stationary deflection roller extend coaxially.
In accordance with a further aspect of the present invention the latter provides a conveying system for the conveying of a product stream of products arranged in an overlapping formation, wherein at least one arriving pressing belt pair and at least two departing pressing belt pairs are provided. A switching mechanism is provided between the arriving and the departing pressing belt pairs and can preferably be formed as described above, whereby the product stream can be selectively directed onto one of the departing pressing belt pairs.